Getting lots of "Deprecated function: Calling static trait method"

I am getting this warning many times when taking the migration list page:

Deprecated function: Calling static trait method Drupal\migrate\Plugin\MigrationDeriverTrait::getSourcePlugin is deprecated, it should only be called on a class using the trait in Drupal\workbench_moderation_migrate\Plugin\migrate\WorkbenchModerationFlowDeriver->getDerivativeDefinitions() (line 24 of modules/contrib/workbench_moderation_migrate/src/Plugin/migrate/WorkbenchModerationFlowDeriver.php).

I see it caused by same reason as #3239442: Calling static trait method is deprecated in PHP 8.1 →